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Kohlrabi is a cultivated form of cabbage, but has a much milder taste. This tasty and fast-growing vegetable finds space in even the smallest of gardens. It only takes a few weeks from sowing to harvesting, which is possible until autumn. Both the tubers and the young leaves are suitable for consumption. However, it can happen that the tubers burst, which can have different causes.

Kohlrabi bursts open

If a kohlrabi bursts, this is mainly due to an unfavorable water supply. Other factors that are responsible for the kohlrabi bursting can be longer periods of cold during the cultivation of young plants, over-fertilization and pest infestation. Depending on what caused the tubers to burst, there are a number of things you can do to prevent them, but also to combat pests, for example.

Kohlrabi prefers a humus-rich soil


Irregular water supply as the main cause

Plants need water for all metabolic processes. If this is only available irregularly, the kohlrabi may burst. It can survive dry and hot periods with occasional watering. An abrupt change in weather in the form of heavy rains can cause cracks in the tubers.

Sensitive vegetable

The kohlrabi is one of the vegetables that react particularly sensitively to changing soil moisture. If the drought persists, plants store lignin in their cell walls. Lignin causes cells to lignify. The plant tissue becomes firmer and more impermeable, the tuber outer walls harden. If there is heavy rainfall or if too much water is poured, the interior of the cell expands and the tuber begins to grow again. The outer cell walls cannot cope with the pressure. They cannot expand sufficiently and the tuber bursts open.


In order to prevent kohlrabi from bursting, such stagnation of growth must be avoided when tubers begin to form. This requires an even supply of water. Dry periods in particular should be bridged by regular and balanced watering.

  • do not water the kohlrabi plants too much or too little
  • Soil should always be evenly moist
  • Water supply should not come to a standstill during the cultivation period
  • from March to April usually no additional watering necessary
  • later water regularly and evenly
  • a larger amount of water once a day is not recommended
  • Soil can only absorb a certain amount of water, a maximum of 10 l per m² and hour
  • it is better to water at intervals, this promotes water absorption
  • two to three times a day, preferably in the morning and evening
  • If possible, only water on the ground and not over the plants
  • otherwise there is a risk of infestation with putrefactive organisms
Kohlrabi in the vegetable patch

Strong fluctuations in soil moisture can also be minimized with a layer of mulch. It is best to wait until May to apply a layer of mulch made from organic materials, by which time the soil will have warmed up a bit.

Tip: When using wood chips or bark mulch, it is advisable to work some horn shavings or horn meal into the soil beforehand, because wood chips remove nitrogen from the soil.

Long periods of cold

The susceptibility to later cracking can also be favored by longer periods of cold during the cultivation of young plants. To counteract this, you should make sure that the temperatures in spring do not fall below 12 °C for a long time. They should only be planted in the garden when no more night frosts are to be expected. If necessary, the culture can initially be protected from possible night frosts with a fleece.


Cracks in kohlrabi can also result from over-fertilization, especially with nitrogen, and in connection with an uneven water supply. The kohlrabi is one of the middle feeders. In order to meet the nutrient requirements and prevent the tubers from bursting open, it is recommended to prepare the soil in autumn with mature compost or horse manure. It is then left to rest over the winter. During the growth, the kohlrabi can be supplied with small doses of diluted nettle manure.

Kohlrabi is a tasty vegetable

pest infestation

Cabbage shoot weevil and rape stalk weevil

Among the pests that are held responsible for the bursting of kohlrabi bulbs cabbage weevil and rapeseed weevil, especially their larvae. It is assumed that the beetles lay their eggs below the growing point or on the tuber and that they release certain substances that cause growth disorders and the tuber to burst. the rape weevil mainly occurs in the vicinity of rapeseed fields. Another assumption is that the larvae eat burrows in both the petioles and the outer layer of the tubers, which they then burst open.

prevention and control

  • Fleece or close-meshed crop protection nets offer protection
  • if necessary, the use of an appropriate insecticide
  • Always think carefully about the use of such resources
  • Apply insecticides before egg laying, 7-10 days after first flight
  • Use of natural predators such as the swede sawfly
  • the ultimate way to identify an infestation is yellow peel
  • they are used to record and control the approach

Tip: To guard against these pests, a three-year grow hiatus should be followed, which includes all cruciferous vegetables. In addition, attention should be paid to suitable plant neighbors such as peas, bush beans, chard, lettuce, spinach and tomatoes as well as marigolds and marigolds.


In areas with high rainfall, slugs that eat the tubers are also held responsible for their bursting. As a preventative measure, old bark mulch, in which there are many snail eggs, should be removed and renewed in early spring. Otherwise can snail fences or biological slug pellets be helpful.

apply slug pellets

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